The present invention relates generally to abraiding through the use of rotary lapping systems, and is specifically directed to the use and configuration of grinding pads, called tesserae, which produce a negative lift effect in high speed lap grinding.
Rotary lapping systems are used to remove material from a variety of types of workpieces. These workpieces include large lightweight, odd-shaped, infrared quality aspheric mirrors, and other optical elements, which are manufactured through a succession of grinding and polishing with rotary lapping systems.
A review of optical surfacing techniques indicates that two-thirds of the manufacturing time is spent polishing out subsurface damage from grinding. The lightweight optical elements and mirrors of orbiting telescopes will be extremely thin (e.g., 3 mm) and aspheric with changing surface curvature. The use of very thin glass sections limits the use of grinding and polishing pressures, yet there exists a need to process large sections of aspheric optical systems in a rapid and efficient manner, while avoiding deformation of the optical surface of the workpiece. While optical surface tolerances are less difficult to meet in infrared systems, eventually the next generation of space telesopes will require quality suitability for visible-spectrum use.
In view of the foregoing discussion it is apparent that there currently exists the need for a rotary lapping system capable of generating strong cutting pressures between the tool and the workpiece, while placing no net downward force on the workpiece. The present invention is directed towards satisfying that need.